Gasoline engine fuel

ABSTRACT

Recession of exhaust valves in gasoline engines operating on lead-free fuel resulting from erosion of the cast iron seats is inhibited by adding to the fuel an overbased, oil soluble sulfonate of a Group II metal, thereby forming on the valve seats a protective deposit of Group II metal compound.

United States Patent [191 [111 3,898,055

Bray Aug. 5, 1975 [54] GASOLINE ENGINE FUEL 3,437,465 4/1969 Lesuer 44/51 [75] Inventor: Ulric B. Bray, Pasadena, Calif. FOREIGN PATENTS OR APPLICATIONS Agsignee; Bray Co Los Angeles Australia 44/76 Flled' June 1971 Primary ExaminerDaniel E. Wyman [21] App]. No.'. 150,788 Assistant ExaminerY. H. Smith Attorney, Agent, or FirmVanderveer Voorhees; 52 us. Cl. 44/51; 44/68; 44/76 Thomas Schenach [51] Int. Cl. COIL 1/24 {58] Field of Search 44/51, 68, 76; 252/395 [57] ABSTRACT C Recession of exhaust valves in gasoline engines oper- [56] References ating on lead-free fuel resulting from erosion of the UNITED STATES PATENTS cast iron seats is inhibited by adding to the fuel an 2,585.520 2/1952 Van Ess et overbased, oil soluble sulfonate of a Group II metal, 2,695,910 1 H1954 Asseff et al. thereby forming on the valve seats a protective deposit Rudel Ct 21]. of Group metal compound 3,342,733 9/1967 Robbins et 3.350.308 10/1967 McMillen 44/76 2 Claims, No Drawings GASOLINE ENGINE FUEL This invention relates to improved fuels for gasoline engines and particularly engines operating on lead-free gasoline where erosion of cast iron exhaust valve seats has become a serious problem. It has been found that engines operating at high load conditions on lead-free gasoline develop a condition known as valve recession" or sinking of the exhaust valves. The result is, of course, erratic operation of the engine and serious loss of power. The cause appears to be associated with formation of highly abrasive iron oxide at the valve seats at the high temperatures and high gas velocities at this area. With leaded fuels, the lead compounds, oxide, bromide, etc., served to prevent this abrasive action. In the absence of the lead, however, exhaust valves were found to sink as much as 1 to 5 mm. in only hours of operation at full load.

We have now discovered that protection can be pro vided for the valves by incorporating in the fuel an oil soluble sulfonate of an alkaline earth metal, particularly calcium, barium, and magnesium, wherein the sulfonate has been overbased by colloidal carbonate to the extent of at least 50 mg. per gram KOH equivalent. In the operation of the engine, the colloidal carbonate is deposited on the valve seats in the form of nonabrasive oxide or other salt, thereby preventing the erosion. The amount of sulfonate needed is usually about 0.5 to 5.0 grams per gallon of fuel. It is desirable that the colloidal carbonate particles have a dimension below l micron and preferably below 0.1 micron sufficiently small to give a transparent dispersion in the fuel, without possibility of sedimentation.

Sulfonate for this purpose can be made by sulfonation of lubricating oil distillates having a molecular weight in the range of 400 to 600, using S0 or oleum of 20 to 25% S0 content in a manner well known in the art. Sulfonated alkyl benzenes, particularly alkylates having straight chain alkyl substituents, are also satisfactory. Metals of Group 11 of the Periodic System are desirable, owing to the refractory nature of their oxides. These sulfonates are then overbased to an alkali value of 200 to 400 mg. KOH per gram equivalent by treating with metal oxides and CO usually in presence of methanol. These reactions are described more fully in the following US. Pat. Nos.: 3,105,049; 3,155,616; 3,155,617; 3,170,880; 3,170,8881; 3,318,809.

We may also add to the fuel a small amount of a phosphorous compound which is soluble in the gasoline, such as the hydrocarbon phosphonates or the oil soluble phosphoric acid esters in an amount stoichiometrically equivalent to the metal in the colloidal carbonate. During combustion, these compounds are oxidized to acids of phosphorous represented by the oxides, P O P 0 and P 0 At high temperature in the presence of the carbonate, the latter can form the pyrophosphate such as Ca P 0 Readily obtainable phosphate esters are the tricresyl phosphate and the trioctyl phosphate. Phosphonates can be made by treating higher molecular weight olefines such as butylene trimer having upwards of 12 carbon atoms with P 5 followed by hydrolysis and neutralization, for example,

with ammonia, an amine, or the hydroxide of a metal such as barium, calcium, or magnesium.

EXAMPLE To 1 gallon of lead-free gasoline, there are added 2 grams of a calcium mahogany sulfonate having a concentration of 40% calcium sulfonate of molecular weight 470 and containing sufficient colloidal calcium carbonate to titrate 300 alkali value using methyl orange indicator and less than 30 when using phenolphthalein indicator. It is necessary that the sulfonate contain very little alkali titratable by phenolphthalein when phosphate esters are present as, otherwise, it may cause hydrolysis of any phosphate ester employed in the fuel.

The above sulfonate dosage containing 600 mg. KOH equivalent per gallon of gasoline will produce, on combustion, 300 mg. CaO which can be converted to 680 mg. of Ca P 0 by adding to the fuel 1,980 mg. (1.98 gm.) tricresyl phosphate (T.C.P.) or approximately an equal weight of T.C.P. and 300 alkali value sulfonate.

Having thus described my invention, what 1 claim is:

l. The method of preventing erosion of cast iron exhaust valve seats in an internal combustion engine operating on lead-free gasoline fuel which comprises incorporating in said fuel from 0.5 to 5.0 grams per gallon of an overbased oil soluble sulfonate of a Group 11 metal having an alkali value of at least 50 mg. KOH per gram equivalent from transparent colloidally dispersed Group 11 metal carbonate sufficient to inhibit the erosion and recession of said exhaust valves and burning said fuel in said engine.

2. The method of claim 1 wherein there is also incorporated in said fuel an oil soluble organic phosphorous compound selected from the class consisting of the phosphoric acid esters and the phosphonates made by treating higher molecular weight olefines having upward of 12 carbon atoms with P S followed by hydrolysis and neutralization, yielding phosphoric acid on combustion in an amount which is substantially equivalent, stoichometrically, to said colloidal carbonate. 

1. THE METHOD OF PREVENTING EROSION OF CAST IRON EXHAUST VALVE SEATS IN AN INTERNAL COMBUSTION ENGINE OPERATING ON LEAD-FREE GASOLINE FUEL WHICH COMPRISES INCORPORATING IN SAID FUEL FROM 0.5 TO 5.0 GRAMS PER GALLON OF AN OVERBASED OIL SOLUBLE SULFONATE OF A GROUP II METAL HAVING AN ALKALI VALUE OF AT LEAST 50 MG. KOH PER GRAM EQUIVALENT FROM TRANSPARENT COLLOIDALLY DISPERSED GROUP II METAL CARBONATE SUFFICIENT TO INHINIT THE EROSION AND RECESSION OF SAID EXHAUST VALVES AND BURNING SAID FUEL IN SAID ENGINE.
 2. The method of claim 1 wherein there is also incorporated in said fuel an oil soluble organic phosphorous compound selected from the class consisting of the phosphoric acid esters and the phosphonates made by treating higher molecular weight olefines having upward of 12 carbon atoms with P2S5 followed by hydrolysis and neutralization, yielding phosphoric acid on combustion in an amount which is substantially equivalent, stoichometrically, to said colloidal carbonate. 